1. Technical Field
The present disclosure relates generally to touch-sensitive electronic components and light emitting diodes (LEDs), and more particularly to an LED switch device and array.
2. Related Art
LEDs are ubiquitous output devices that find many applications across a variety of fields for their high efficiency, fast switching, and extended longevity, among other advantages. One of the most common utility is as indicators for electronic devices, and so LEDs are available in packages of different shapes and sizes to suit the particular application. Additionally, different illumination colors or radiation wavelengths across the visible spectrum are available, from the low wavelength red to the high wavelength violet. Several LEDs can be combined into arrays, with each LED being independently driven to generate visible patterns representative of text and graphics. Beyond the visible spectrum, however, there are LEDs capable of emitting infrared waves, which are typically utilized for inter-device communications. At the opposing end of the spectrum, ultraviolet waves may be utilized for sterilizing, sanitizing and disinfecting purposes. Although a typical miniature LED indicator light has an operating current of around 20 mA with less than 1 lumen of output, some recent high power LEDs are capable of operating currents of hundreds of mA and over a thousand lumens of output, which can serve as substitutes for incandescent bulbs in lighting applications.
The operational principles of LED devices are well known, with a central part being a semiconductor material that is doped to create a P-N junction. The anode, or the P-side of the junction is connected to a positive terminal of a power supply, while the cathode, or the N-side of the junction, is connected to a negative or common terminal of the power supply. As electricity flows between the P-N junction, energy in the form of a light photon is released. Whether utilized as a miniature, low power indicator or as a high-intensity illuminator, LEDs operate in this manner. In some applications, an LED can be utilized as a photodetector, where photons of light falling on the P-N junction are converted to an electrical signal. Instead of being connected to a power supply, the LED may be connected to a detection circuit to produce a response upon receiving a signal therefrom.
Except in the aforementioned application as a photodetector, packaged LED devices are generally considered basic output devices. As noted, an array of LEDs can be devised with each one being controlled individually in order to generate coherent visual patterns. Direct user interactions with such visual outputs over display arrays have been contemplated, but such devices have involved a separate input device that is overlaid on the output device. One example is a capacitive touch screen utilized in slate computing devices such as TabletPCs from various manufacturers and the iPad® from Apple, Inc. of Cupertino, Calif.
These devices are known to utilize a transparent or semi-transparent sensor panel comprised of rows and columns of traces on opposite sides of a dielectric. The traces are comprised of indium tin oxide or antimony tin oxide, with a top glass panel being etched with the column traces and a bottom glass panel being etched with the row traces. For the touch sensor panel to be transparent, the etched traces are around 30 microns. Separating the top glass panel and the bottom glass panel may be a transparent polymer spacer that serves as the dielectric between the column traces and the row traces. The sensor panels are then mounted in an overlapping relationship to the liquid crystal display (LCD).
Another example of incorporating simultaneous input and output capabilities in displays, albeit on a slightly larger scale, are LED matrices with switches close to the LEDs. One known device is disclosed in U.S. Pat. No. 5,638,052 to Furuya, et al, which discloses an array of LEDs with switches for turning on or turning off individual LEDs being provided at locations corresponding to or close to the LEDs. The Sensacell device produced by Sensacell Inc. of Brooklyn, N.Y. is similar to the Furuya, et al. device, except for the use of capacitive sensors disposed amongst a matrix of LEDs each forming a unit of inter-connectible cells.
In these earlier systems, the output or display device is configured independently from the input device. Accordingly, there is a need in the art for an integrated LED switch device and array.